1. Especially in Brazil, the Negroes have played __________ most important role in the development of the nation, but they are still living on _________ poverty line.
A. the; the           B. a; the                    C. a; 不填               D. the; 不填
2. --- Mothers are always the greatest persons in the world and they have been doing a lot for us.
--- Of course, I used to feel _______ a terrible thing that my mother should have to work so hard and endlessly to support her family.
A. it                        B. that                   C. this                 D. which